The present invention relates to a sub frame structure of an automotive vehicle.
In an automotive vehicle, a sub frame is attached to a vehicle-body rear portion and suspension links and other components are attached to the sub frame. In general, the sub frame to which the suspension links are previously assembled is attached to the vehicle-body rear portion from below.
Increasing the rigidity of a vehicle body where the suspension links are attached can generally improve the driver's feelings of responsibility and rigidity when the automotive vehicle makes a turn. Japanese Patent Laid-Open Publication No. 2009-114652 proposes that a brace member is additionally provided to increase the rigidity of the vehicle body where the suspension links are attached.
Improving the fuel economy has been recently desired additionally for the rigidity improvement. Accordingly, it is desirable that the sub frame is made properly light, ensuring the necessary rigidity thereof. The structure disclosed in the above-described patent document is superior in the rigidity improvement, but inferior in the light weight because of the brace member additionally provided as a reinforcing member.
Moreover, the sub frame to which the suspension links are attached requires the rigidity for supporting components properly against an external force transmitted from a wheel. Especially, in a case in which the number of suspension links is large like a multilink type of suspension, the number of attachment portions for attaching the suspension links which are provided at the sub frame becomes large as well. Accordingly, if each of the attachment portions for the suspension links is reinforced, the light weight of the sub frame may not be obtained.